Core barrel valve assembly

ABSTRACT

The present invention relates to a method for a valve, which valve comprises a movable valve body ( 6 ) having a first side ( 9 ) facing a means for supplying pressurized fluid and influenced in the supply direction by a force from said fluid, and a second side ( 11 ) influenced in opposite direction by a force from said fluid, which valve is provided with at least one connection ( 8 ) connecting the first side ( 9 ) of the valve body with the second side ( 11 ) of the valve body, and also comprising a spring ( 20 ) for opening the valve by displacing the valve body from a closed position to an open position, said method comprising the following steps: a pressurized fluid is supplied to the valve in closed position so that the valve remains closed; the supply of pressurised fluid to the closed valve ceases, a force equalization then occurs between said first ( 9 ) and second ( 11 ) sides thereby enabling the spring to open the valve, and a pressurized fluid is supplied to the valve in open position and the valve remains open. The invention also relates to a valve for performing the method and to a system for wire line core drilling including such a valve.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national counterpart application ofinternational application serial No. PCT/SE00/01631 filed Aug. 24, 2000,which claims priority to Swedish application serial no. 9903019-9 filedAug. 24, 1999.

The present invention relates to a method for a valve, a valve and awire line core drilling system including such a valve.

It is known in various connections to use valves that control the supplyof a fluid by being opened when they are subjected to a certain pressurefrom the fluid. One such application is in wire line core drilling, aswill be described below.

When performing exploratory drilling to collect rock samples from depthsof from several hundred to a couple of thousand meters, double coretubes are used having an inner and an outer tube. The sample iscollected in the inner tube, which usually has a length of a few meters.When the inner tube is full this is usually detected by means of amanometer or the like that measures the flushing water pressure in thecore tube. A retriever device suspended on a wire is lowered into thetube for retracting the inner tube with the sample, said retrieverdevice comprising a gripping means in the form of a claw or “spearhead”arranged to engage with a gripping means arranged on/in the upper end ofthe inner tube. When the wire is then tautened the inner tube isdisengaged from the outer tube, and the inner tube with the sample canbe hoisted up. Conversely, the claw and the gripping means on the innertube can be used to lower a new inner tube. Equipment of this type isgenerally known as a wire line system.

When a new inner tube is inserted it is important to be able toascertain that the inner tube really has reached right down to thebottom of the outer tube and has assumed its correct position fordrilling, before drilling is commenced. Ascertainment that the tube canno longer move, but is firmly held is generally taken as an indicationthat the inner tube has reached its correct position. According to knowntechnology, therefore, the gripping means is often designed to becombined with some type of locking member that firmly locks the innertube in relation to the outer tube when the inner tube has reached thecorrect position. This locking member usually consists of a hook-likedevice, preferably spring-loaded, a locking claw or latch that engageswith recesses or shoulders arranged in the inside of the outer tube.Actual insertion of the inner tube is usually performed by the innertube being “pumped” along inside the drill string with the aid of water.When the inner tube is firmly in place the water pressure will increaseto such an extent that a valve arranged for flushing medium in the innertube is released.

One problem with such known arrangements is that when the inner tube isinserted into the drill string it sometimes catches before it hasreached the correct position for drilling. With designs currently inuse, the increase in water pressure then occurring will release theflushing valve before the inner tube has reached its correct positionand, in the worst case, drilling will be commenced. This primarilyentails a disadvantage from the financial point of view since thedrilling will be into thin air. There is also a risk of the core at thebottom being destroyed.

The primary object of the present invention is to remedy the problemsdescribed above.

The object of the invention is achieved by means of a method as definedin claim 1, a valve as defined in claim 5, and a wire line core drillingsystem as defined in claim 9.

In accordance with the present invention, therefore, a method is definedfor a valve, which valve comprises a movable valve body having a firstside facing a means for supplying pressurised fluid and influenced inthe supply direction by a force from said fluid, and a second sideinfluenced in opposite direction by a force from said fluid, which valveis provided with at least one connection connecting the first side ofthe valve body with the second side of the valve body, and alsocomprising a spring for opening the valve by displacing the valve bodyfrom a closed position to an open position, said method comprising thefollowing steps:

a pressurised fluid is supplied to the valve in closed positionwhereupon the valve remains closed,

the supply of pressurised fluid to the closed valve ceases,

a force equalisation then occurs between said first and second sides inthat fluid flows through the connection, thereby enabling the spring toopen the valve, and

a pressurised fluid is supplied to the valve in open position and thevalve remains open.

The present invention thus offers the advantage that the valve is notopened immediately an increase in pressure is obtained, but opening isdelayed. This is particularly advantageous, for instance, when the valveis being used in conjunction with a wire line core drill.

The valve is advantageously provided with a locking device tomechanically lock the valve when it is in closed position, and themethod then comprises the following favourable features:

the pressurised fluid is supplied to the valve in closed andmechanically locked position,

the locking device is caused to cease locking said valve in closedposition,

the valve continues to be closed even when the locking device no longerlocks the valve, since the pressurised fluid supplied still causes thevalve to remain closed,

the supply of pressurised fluid ceases, and

a force equalisation then occurs between said first and second sides,thereby enabling the spring to open the valve.

The features defined above offer the advantage of double security, sincethe valve not only has delay function, but is also mechanically lockedin closed position.

The method is performed using a valve as defined in claim 5.

In accordance with the particularly advantageous application of theinvention in wire line core drilling, the advantages are obtained thatthe flush valve is not released until the inner tube has assumed thecorrect position inside the outer tube for drilling and that when thevalve is released, this occurs mechanically with the aid of the lockingdevice in accordance with the invention. It is thus not released as aresult of an increase in pressure, and the risks associated withpreviously known pressure-released arrangements are thereforeeliminated. There is therefore no risk of drilling being commencedbefore the inner tube is safely in place. The completion of all steps inthe method may also be used with advantage as an indication that theinner tube has assumed the correct position in the outer tube and thatdrilling may be commenced. For this purpose a signal may be conveyed toa drill rig. This is particularly advantageous with modern,computer-controlled drill rigs. A system for wire line core drillingprovided with a valve in accordance with the invention, thusadvantageously includes means for transmitting a signal to a drill rig,which signal indicates that the inner tube has assumed the correctposition inside the outer tube, that the valve has been opened and thatdrilling can be commenced.

Additional features and advantages are revealed in the subordinateclaims.

The invention will now be described in detail with reference to theaccompanying drawings, illustrating a non-limiting embodiment of theinvention by way of example, in which:

FIG. 1 shows a longitudinal section through a valve, in accordance withthe present invention, in closed position, when used in a drill string,

FIG. 2 shows a longitudinal section through a valve, in accordance withthe present invention, in open position, when used in a drill string,

FIG. 3 shows a partial enlargement of the valve in FIG. 1, in closedposition,

FIG. 4 shows a partial enlargement of the valve in FIG. 1, still inclosed position,

FIG. 5 shows a partial enlargement of the valve in FIG. 2, in openposition, and

FIG. 6 shows the locking device, gripping means, valve and inner tubebefore the inner tube arrives at the position where drilling can start.

The embodiment illustrated by way of example shows an applicationwherein a valve in accordance with the present invention is used with asystem for wire line core drilling.

The drill string in FIG. 1 thus comprises an outer tube 1 connected to adrill bit, and an inner tube 2, by means of which core samples arecollected. Drilling is performed towards the right in the drawing, thisbeing designated the forward direction. A valve 5 for flushing medium isarranged in the rear part of the inner tube. The flushing medium isgenerally water. When a new inner tube for core samples is to beinstalled in an existing outer tube for drilling substantially inhorizontal direction or at various upward angles, the inner tube ispumped along inside the drill string with the aid of flushing medium,preferably water. FIG. 1 illustrates the position when the inner tubehas just reached the correct position for drilling but has not yet beenlocked in relation to the outer tube.

A locking device 4 is also arranged in the rear part of the inner tube.As in the example illustrated, this may preferably consist of a lockingdevice such as is the subject of the applicant's own Swedish patentapplication filed simultaneously with the present patent application.This locking device not only locks the valve in closed positionmechanically, but also firmly retains the inner tube in relation to theouter tube when the inner tube has assumed the correct position fordrilling. This occurs by the forward, outwardly directed protrusions 24of the locking device rebounding and engaging with correspondingrecesses 25 on the inside of the outer tube, as illustrated in FIGS. 4and 5. In other applications it is naturally feasible to use a lockingdevice that only retains the valve mechanically.

The valve 5 comprises a valve body 6 movable between a closed positionas shown in FIG. 1 and an open position as shown in FIG. 2. For aclearer picture of the valve, reference is made in the followingprimarily to FIGS. 3 to 5, showing enlarged-views of the valve. Thevalve 6 is provided with a communication or a connection 8 connectingthe first, rear side 9 of the valve body, comprising a surface 10 facingthe direction in which the pressurised fluid is supplied, with a second,forward side 11 consisting of two surfaces 12, 14. The connection 8 mayalternatively be described as connecting a space 15 behind the valvebody or piston 6 with a space in front of the valve body which, in theexample illustrated, is a space 16 situated inside the valve body.

In the embodiment illustrated by way of example the valve body 6 isjoined to a gripping means 22 which, in co-operation with the previouslymentioned locking device 4, mechanically maintains the valve body in itsclosed position. This is achieved by the locking device having inwardlydirected protrusions 23 that grip around the gripping means 22. Thegripping means 22 is secured in the valve body by its forward end 27being screwed into an axial hole 28, provided with threading, in therear end of the valve body. Said hole is open to the space 16 inside thevalve body. To achieve said connection 8 between the space 16 and thespace 15 behind the valve body, therefore, the forward part 27 of thegripping means 22 is provided with an axial boring or a hole, open tothe space 16, and a radial hole connected thereto and to the space 15.In the present embodiment, therefore, the connection 8 comprises twoparts—an axial hole and a radial hole. It is naturally perfectlyfeasible to secure the gripping means in the valve body by means of someother arrangement, and the appearance and positions of the holes may bemodified without departing from the inventive concept as regards theconnection 8. It should particularly be mentioned that it is possible toarrange the connection 8 directly as a hole through the valve body.

The valve body has a rear part 17 with smaller diameter and a forwardpart 18 with larger diameter. The rear part 17 slides in a housing 19whereas the forward part 18 preferably slides directly inside the innertube 2. A spring 20 is arranged between the housing 19 and the forwardpart 18. In the example illustrated this is a helical spring. It iscompressed when the valve is closed and its spring force thus acts toopen the valve.

When the valve is in its closed position, as shown in FIGS. 1, 3 and 4,and a pressurised fluid in the form of a flushing medium is supplied tothe valve in the direction from the left in the drawings, thispressurised fluid will exert a force F₁ on the surface 10 consisting ofthe rear side 9 of the valve body. Since the fluid will also penetratethrough the valve body via the connection 8, see particularly FIG. 4,the valve body will also be influenced by forces from the fluid in adirection opposite to the supply direction when the fluid pressure actson the surfaces 12 and 14 on the other side 11 of the valve. At the sametime the valve body is influenced by the spring force F_(f). To ensurethat the valve remains in closed position even after the locking devicehas released the valve body, as shown in FIG. 4, the follow correlationmust prevail:

F₁+F_(f)<F₂+F₃

where F₁=p·A₁, F₂=p·A₂, F₃=p·A₃,

wherein p is the pressure of the supplied fluid and A₁, A₂, A₃ are theareas of the surfaces 10 on the rear side 9 and 12 and 14 on the frontside 11, respectively, of the valve body.

It should be mentioned that, for the above correlation to prevail inpractice, O-rings 13 are arranged as seals preventing the spacecontaining the spring 20 from being pressurised. An O-ring is thusarranged between the outside of the forward part 18 of the valve bodyand the inside of the inner tube 2, and an O-ring is arranged betweenthe outside of the rear part 17 of the valve body and the inside of thehousing 19.

For the valve to open, the supply of pressurised fluid must be cut offand the fluid placed in communication with atmospheric pressure in orderto achieve pressure equalisation between both sides of the valve body.It will then only be influenced by the spring force, causing the spring20 to expand so that the valve body 6 is moved out of the housing 19 andthe valve is thus open, as illustrated in FIG. 2 and FIG. 5.

In the illustrated use of the valve the inner tube is pumped into theouter tube with a typical pressure of 30 to 40 bar. When the inner tubehas reached its correct position in the outer tube, it is firmly lockedthere, as shown in FIG. 3, i.e. it touches bottom, the pressureincreases to in the order of 50 bar or the maximum pressure for thepump. The pressure is then shut off and the fluid is placed incommunication with atmospheric pressure so that the valve opens, asillustrated in FIG. 5. Thereafter the supply of pressurised fluid isturned on again, at a pressure in the order of 10-20 bar, and this isthen the pressure used during drilling.

The present invention is naturally not limited to the embodiment and theapplication illustrated. It may be varied in many feasible ways withinthe scope of the invention as described in the specification and theappended claims. The valve may thus be used entirely independently andin entirely different contexts, with or without any form of lockingdevice that produces mechanical locking. Furthermore, the method mayalso be used in other contexts and other applications where similarproblems need solving and delayed opening of a valve is desired.

What is claimed is:
 1. A method for a valve, which valve comprises amovable valve body having a first side facing a means for supplyingpressurized fluid and influenced in the supply direction by a force fromsaid fluid, and a second side influenced in opposite direction by aforce from said fluid, which valve is provided with at least one fluidconnection connecting the first side of the valve body with the secondside of the valve body and thereby allowing said supplied pressurizedfluid to flow from said first side to said second side of the valvebody, and also comprising a spring for opening the valve by displacingthe valve body from a closed position to an open position, said methodcomprising the following steps: a pressurized fluid is supplied to thevalve in closed position whereupon the valve remains closed, the supplyof pressurized fluid to the closed valve ceases, a force equalizationthen occurs between said first and second sides in that fluid flowsthrough the fluid connection, thereby enabling the spring to open thevalve, and a pressurized fluid is supplied to the valve in open positionand the valve remains open.
 2. A method for a valve, which valvecomprises a movable valve body having a first side facing a means forsupplying pressurized fluid and influenced in the supply direction by aforce from said fluid, and a second side influenced in oppositedirection by a force from said fluid, which valve is provided with atleast one connection connecting the first side of the valve body withthe second side of the valve body, and also comprising a spring foropening the valve by displacing the valve body from a closed position toan open position, said method comprising the following steps: apressurized fluid is supplied to the valve in closed position whereuponthe valve remains closed, the supply of pressurized fluid to the closedvalve ceases, a force equalization then occurs between said first andsecond sides in that fluid flows through the connection, therebyenabling the spring to open the valve, and a pressurized fluid issupplied to the valve in open position and the valve remains open, thevalve further being provided with a locking device to mechanically locksaid valve when in closed position, which method comprises the followingsteps: the pressurized fluid is supplied to the valve in closed andmechanically locked position, the locking device is caused to ceaselocking said valve in closed position, the valve continues to be closedeven when the locking device no longer locks the valve, since thepressurized fluid supplied still causes the valve to remain closed, thesupply of pressurized fluid ceases, and a force equalization then occursbetween said first and second sides, thereby enabling the spring to openthe valve.
 3. A method as claimed in claim 2 wherein the method is usedwith a valve for a wire line core drill comprising an inner tube bymeans of which core samples are collected, and an outer tube connectedto a drill bit, in that the locking device is applied in the rear end ofthe inner tube, in that said valve is placed at the rear end of theinner tube and controls the supply of a flushing medium in the form of apressurized fluid and wherein, when the inner tube has been inserted inthe outer tube and has assumed the correct position inside the outertube for drilling, in one and the same movement said locking devicesimultaneously achieves locking of the inner tube in relation to theouter tube and releases said valve so that it is no longer mechanicallylocked.
 4. A method as claimed in claim 3 wherein, after the pressurizedfluid is supplied to the valve in closed and mechanically lockedposition, the locking device is caused to cease locking said valve inclosed position, the valve continues to be closed, the supply ofpressurized fluid ceases, and a force equalization occurs between saidfirst and second sides, thereby enabling the spring to open the valve, asignal is conveyed to a drill rig, said signal indicating that the innertube has assumed the correct position inside the outer tube and thatdrilling can be commenced.
 5. A valve comprising a movable valve bodyhaving a first side facing a means for supplying pressurized fluid andhaving at least one first surface that is influenced in the supplydirection by a force F1 from said fluid, and a second side facing in theopposite direction, and which valve is provided with at least one fluidconnection connecting the first side of the valve body with the secondside of the valve body and thereby allowing said supplied pressurizedfluid to flow from said first side to said second side of the valvebody, wherein the valve comprises a spring for opening the valve bydisplacing the valve body from a closed position to an open position, inthat said second side of the valve body has at least one second surfacethat is influenced by a force from said fluid in a direction opposite tothe supply direction, and in that the area of said second surface isgreater than that of said first surface so that the force influencingthe valve body in closing direction, in the form of the force from thepressurized fluid acting on said second surface exceeds the forceinfluencing the valve body in opening direction, in the form of thecombined force Ff from the spring and the force F1 from the pressurizedfluid acting on said first surface, whereby the valve body is retainedin the closed position of the valve when pressurized fluid is supplied.6. A valve as claimed in claim 5 wherein the valve is so designed that,when the supply of pressurized fluid to the closed valve ceases, a forceequalization occurs via said fluid connection between said first andsecond sides, and in that the spring then influences the valve body sothat it is displaced from its closed to its open position.
 7. A valve asclaimed in claim 6 wherein the second surface, on the second side of thevalve body is divided into two surfaces.
 8. A wire line core drillsystem comprising a wire line core drill having an inner tube by meansof which core samples are collected, an outer tube connected to a drillbit, and a valve situated at the rear end of the inner tube, said valvecontrolling the supply of a flushing medium in the form of a pressurizedfluid, wherein the valve is constructed in accordance with claim
 7. 9. Awire line core drill system comprising a wire line core drill having aninner tube by means of which core samples are collected, an outer tubeconnected to a drill bit, and a valve situated at the rear end of theinner tube, said valve controlling the supply of a flushing medium inthe form of a pressurized fluid, wherein the valve is constructed inaccordance with claim
 6. 10. A valve as claimed in claim 5 wherein thesecond surface, on the second side of the valve body, is divided intotwo surfaces.
 11. A wire line core drill system comprising a wire linecore drill having an inner tube by means of which core samples arecollected, an outer tube connected to a drill bit, and a valve situatedat the rear end of the inner tube, said valve controlling the supply ofa flushing medium in the form of a pressurized fluid, wherein the valveis constructed in accordance with claim
 10. 12. A wire line core drillsystem comprising a wire line core drill having an inner tube by meansof which core samples are collected, an outer tube connected to a drillbit, and a valve situated at the rear end of the inner tube, said valvecontrolling the supply of a flushing medium in the form of a pressurizedfluid, wherein the valve is constructed in accordance with claim
 5. 13.A system as claimed in claim 12 including means for transmitting asignal to a drill rig, said signal indicating that the inner tube hasassumed the correct position inside the outer tube and that the valvehas been opened.
 14. A valve comprising a movable valve body having afirst side facing a means for supplying pressurized fluid and having atleast one first surface that is influenced in the supply direction by aforce F1 from said fluid, and a second side facing in the oppositedirection, and which valve is provided with at least one connectionconnecting the first side of the valve body with the second side of thevalve body, wherein the valve comprises a spring for opening the valveby displacing the valve body from a closed position to an open position,in that said second side of the valve body has at least one secondsurface that is influenced by a force from said fluid in a directionopposite to the supply direction, and in that the area of said secondsurface is greater than that of said first surface so that the forceinfluencing the valve body in closing direction, in the form of theforce from the pressurized fluid acting on said second surface exceedsthe force influencing the valve body in opening direction, in the formof the combined force Ff from the spring and the force F1 from thepressurized fluid acting on said first surface, whereby the valve bodyis retained in the closed position of the valve when pressurized fluidis supplied, the valve being provided with a locking device formechanically locking said valve when it is in closed position.
 15. Awire line core drill system comprising a wire line core drill having aninner tube by means of which core samples are collected, an outer tubeconnected to a drill bit, and a valve situated at the rear end of theinner tube, said valve controlling the supply of a flushing medium inthe form of a pressurized fluid, wherein the valve is constructed inaccordance with claim
 14. 16. A wire line core drill system comprising awire line core drill having an inner tube by means of which core samplesare collected, an outer tube connected to a drill bit, and a valvesituated at the rear end of the inner tube, said valve controlling thesupply of a flushing medium in the form of a pressurized fluid, thevalve comprising a movable valve body having a first side facing a meansfor supplying pressurized fluid and having at least one first surfacethat is influenced in the supply direction by a force F1 from saidfluid, and a second side facing in the opposite direction, and whichvalve is provided with at least one connection connecting the first sideof the valve body with the second side of the valve body, wherein thevalve comprises a spring for opening the valve by displacing the valvebody from a closed position to an open position, in that said secondside of the valve body has at least one second surface that isinfluenced by a force from said fluid in a direction opposite to thesupply direction, and in that the area of said second surface is greaterthan that of said first surface so that the force influencing the valvebody in closing direction, in the form of the force from the pressurizedfluid acting on said second surface exceeds the force influencing thevalve body in opening direction, in the form of the combined force Fffrom the spring and the force F1 from the pressurized fluid acting onsaid first surface, whereby the valve body is retained in the closedposition of the valve when pressurized fluid is supplied, the valvebeing provided with a locking device for mechanically locking said valvewhen it is in closed position, wherein the valve provided with thelocking device is applied in the rear end of the inner tube and in thatsaid locking device is so constructed that, when the inner tube has beeninserted in the outer tube and has assumed the correct position insidethe outer tube for drilling, in one and the same movement itsimultaneously achieves locking of the inner tube in relation to theouter tube and releases said valve so that it is no longer mechanicallylocked.
 17. A valve comprising a movable valve body having a first sidefacing a means for supplying pressurized fluid and having at least onefirst surface that is influenced in the supply direction by a force F1from said fluid, and a second side facing in the opposite direction, andwhich valve is provided with at least one connection connecting thefirst side of the valve body with the second side of the valve body,wherein the valve comprises a spring for opening the valve by displacingthe valve body from a closed position to an open position, in that saidsecond side of the valve body has at least one second surface that isinfluenced by a force from said fluid in a direction opposite to thesupply direction, and in that the area of said second surface is greaterthan that of said first surface so that the force influencing the valvebody in closing direction, in the form of the force from the pressurizedfluid acting on said second surface exceeds the force influencing thevalve body in opening direction, in the form of the combined force Fffrom the spring and the force F1 from the pressurized fluid acting onsaid first surface, whereby the valve body is retained in the closedposition of the valve when pressurized fluid is supplied, the valvebeing so designed that, when the supply of pressurized fluid to theclosed valve ceases, a force equalization occurs via said connectionbetween said first and second sides, and in that the spring theninfluences the valve body so that it is displaced from its closed to itsopen position, the valve being provided with a locking device formechanically locking said valve when it is in closed position.
 18. Awire line core drill system comprising a wire line core drill having aninner tube by means of which core samples are collected, an outer tubeconnected to a drill bit, and a valve situated at the rear end of theinner tube, said valve controlling the supply of a flushing medium inthe form of a pressurized fluid, wherein the valve is constructed inaccordance with claim
 17. 19. A valve comprising a movable valve bodyhaving a first side facing a means for supplying pressurized fluid andhaving at least one first surface that is influenced in the supplydirection by a force F1 from said fluid, and a second side facing in theopposite direction, and which valve is provided with at least oneconnection connecting the first side of the valve body with the secondside of the valve body, wherein the valve comprises a spring for openingthe valve by displacing the valve body from a closed position to an openposition, in that said second side of the valve body has at least onesecond surface that is influenced by a force from said fluid in adirection opposite to the supply direction, and in that the area of saidsecond surface is greater than that of said first surface so that theforce influencing the valve body in closing direction, in the form ofthe force from the pressurized fluid acting on said second surfaceexceeds the force influencing the valve body in opening direction, inthe form of the combined force Ff from the spring and the force F1 fromthe pressurized fluid acting on said first surface, whereby the valvebody is retained in the closed position of the valve when pressurizedfluid is supplied, the second surface, on the second side of the valvebody, being divided into two surfaces, the valve s being provided with alocking device for mechanically locking said valve when it is in closedposition.
 20. A wire line core drill system comprising a wire line coredrill having an inner tube by means of which core samples are collected,an outer tube connected to a drill bit, and a valve situated at the rearend of the inner tube, said valve controlling the supply of a flushingmedium in the form of a pressurized fluid, wherein the valve isconstructed in accordance with claim
 19. 21. A valve comprising amovable valve body having a first side facing a means for supplyingpressurized fluid and having at least one first surface that isinfluenced in the supply direction by a force F1 from said fluid, and asecond side facing in the opposite direction, and which valve isprovided with at least one connection connecting the first side of thevalve body with the second side of the valve body, wherein the valvecomprises a spring for opening the valve by displacing the valve bodyfrom a closed position to an open position, in that said second side ofthe valve body has at least one second surface that is influenced by aforce from said fluid in a direction opposite to the supply direction,and in that the area of said second surface is greater than that of saidfirst surface so that the force influencing the valve body in closingdirection, in the form of the force from the pressurized fluid acting onsaid second surface exceeds the force influencing the valve body inopening direction, in the form of the combined force Ff from the springand the force F1 from the pressurized fluid acting on said firstsurface, whereby the valve body is retained in the closed position ofthe valve when pressurized fluid is supplied, the valve being sodesigned that, when the supply of pressurized fluid to the closed valveceases, a force equalization occurs via said connection between saidfirst and second sides, and in that the spring then influences the valvebody so that it is displaced from its closed to its open position, thesecond surface, on the second side of the valve body being divided intotwo surfaces, the valve being provided with a locking device formechanically locking said valve when it is in closed position.
 22. Awire line core drill system comprising a wire line core drill having aninner tube by means of which core samples are collected, an outer tubeconnected to a drill bit, and a valve situated at the rear end of theinner tube, said valve controlling the supply of a flushing medium inthe form of a pressurized fluid, wherein the valve is constructed inaccordance with claim 21.